The present invention relates to a method, an apparatus and an installation for the direct continuous measurement of thermal energy transferred by a fluid medium to an exchanger for the heating or cooling of rooms, and the collection, memorization and distance transmission of the principal parameters of the system and relative apparatuses controlling the operation of the equipment.
Apparatus for direct measurement of the thermal energy transferred by a fluid medium are known, but they present some problems relative to the stability of operation, associated with the reference current, causing inaccurate operation. In particular, U.S. Pat. No. 3,617,713 describes an apparatus measuring temperature differences and heat quantities in a fluid in motion by means of signals proportional to the difference of temperature between two points of the fluid conduit and to the volume of fluid measured by a volume meter. It does not, however, give the absolute certainty that in case of a nul difference of temperature that there will be no totalization of energy. Similarly, an article entitled "New Resistance to Frequency Converter for Temperature Measurements in Calorimeters" by R. Friedl and P. Seyfried, published in IEEE Transactions on Instrumentation and Measurement, Vol. IM-24, No. 4, p. 322-324, December 1975, describes a circuit for the measurement of the difference of temperature between input and output of heat exchangers by means of resistance thermometers. Two thermometric resistances are part of a resistance to frequency converter, the frequency being proportional to their difference of resistance value. Moreover, the frequency depends upon some resistors and an added condenser. This circuit had been implemented to be used in a simple and reliable calorimeter for household use. However, such a circuit did not provide for the case of complete cancellation of any possible thermal drift due to variation of voltage and ambient temperature.